Hi Ellen, thank you for stopping by our site!
I have to admit, I am one of those people who's garage door did not come with any built-in windows and every time I have to find something in the garage during daytime, I think about having the door rebuilt and adding one row with windows so I can use some of that bright light outside instead of relying on the light overhead and another puny one in the door opener motor. I keep putting that off for that is not a minor project and I'm honestly surprised that someone might want to limit amount of light available in the garage 'cause I always feel there isn't enough.
That said, however, my garage is facing north and if yours is facing west and you live in a southern location, I can understand that for a few hours a day the sun may be a little too much. Besides, if you have one of those all-glass garage doors, it would obviously be much different.
Unless you do, in fact, have an all-glass garage door, there's no reason to worry about air expansion due to tinting because the panes are too small for the air to expand much.Â
If your garage door is all-glass, you should still be fine. Some window tint film manufacturers like 3M for their Prestige window tint films, offer warranty against window damage due to effects of the film. Additionally, the cracking occurs because the external pane bows out too much since the film not only helps heating the air between the panes but also restricts movement of the internal pane. In the case of an all-glass garage door, the external pane would be reinforced by the glue that's holding it to the frame, and so the effects of the air expansion would be somewhat less pronounced.
There are also films you can mount on the outside that would eliminate most of these concerns. Again, I can recommend 3M as probably the best recognized name in the film (of any kind) industry:
One other thing: you can install the film on only one of the sections and watch the effects for awhile. If you don't see any increased bowing on that particular section on a hot sunny day, you can then add film to the rest of the door.